Question

Three children in a family have blood types O, AB and B respectively. What are the genotypes of their parents?

• A. $I^{A}I$ and $I^{B}I$
• B. $I^A{I}^B$ and $II$
• C. $I^B{I}^B$ and $I^A{I}^A$
• D. $I^A{I}^A$ and $I^{B}I$

Answer 1

The correct option is A $I^{A}I$ and $I^{B}I$

Only when the genotype of parents is heterozygous for A and B blood group, (present in any of the parent), three different phenotypes of blood groups are possible in the progeny. All the types of blood group would be present in 25% frequency resulting in the formation of A, B, AB and O type of blood group.